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1.	Andersen, Martin, et al. (författare) Distributed Robust Stability Analysis of Interconnected Uncertain Systems 2012 Ingår i: Proceedings of the 51st IEEE Conference on Decision and Control. - 0743-1546. - 9781467320641 - 9781467320658 ; , s. 1548-1553 Konferensbidrag (refereegranskat)abstract This paper considers robust stability analysis of a large network of interconnected uncertain systems. To avoid analyzing the entire network as a single large, lumped system, we model the network interconnections with integral quadratic constraints. This approach yields a sparse linear matrix inequality which can be decomposed into a set of smaller, coupled linear matrix inequalities. This allows us to solve the analysis problem efficiently and in a distributed manner. We also show that the decomposed problem is equivalent to the original robustness analysis problem, and hence our method does not introduce additional conservativeness.
2.	Andersson, Joel, et al. (författare) Dynamic optimization with CasADi 2012 Ingår i: IEEE 51st Annual Conference on Decision and Control (CDC), 2012. - 0743-1546. - 9781467320658 ; , s. 681-686 Konferensbidrag (refereegranskat)abstract We demonstrate how CasADi, a recently devel- oped, free, open-source, general purpose software tool for nonlinear optimization, can be used for dynamic optimization in a flexible, interactive and numerically efficient way. CasADi is best described as a minimalistic computer al- gebra system (CAS) implementing automatic differentiation (AD) in eight different flavors. Similar to algebraic modeling languages like AMPL or GAMS, it includes high-level interfaces to state-of-the-art numerical codes for nonlinear program- ming, quadratic programming and integration of differential- algebraic equations. CasADi is implemented in self-contained C++ code and contains full-featured front-ends to Python and Octave for rapid prototyping. In this paper, we discuss CasADi from the perspective of the developer or advanced user of algorithms for dynamic optimization for the first time, leaving out details on the implementation of the tool. We demonstrate how the tool can be used to model highly complex dynamical systems directly or import existing models formulated in the algebraic modeling language AMPL or the physical modeling language Modelica. Given this symbolic representation of the process models, the resulting optimal control problem can be solved using a vari- ety of methods, including transcription methods (collocation), methods with embedded integrators (multiple shooting) as well as indirect methods.
3.	Filieri, Antonio, et al. (författare) Autotuning control structures for reliability-driven dynamic binding 2012 Ingår i: IEEE 51st Annual Conference on Decision and Control (CDC), 2012. - 0743-1546. - 9781467320658 ; , s. 418-423 Konferensbidrag (refereegranskat)abstract This paper explores a formally grounded ap- proach to solve the problem of dynamic binding in service- oriented software architecture. Dynamic binding is a widely adopted mean to automatically bind exposed software interfaces to actual implementations. The execution of an operation on one or another implementation, though providing the same result, could turn out in different quality of service, e.g. due to failure occurrence. Dynamic binding is thus of primary importance to achieve what in the Software Engineering domain is called “self- adaptiveness”, the capability to preserve a desired quality of service, if this is feasible. It is important to reach this goal also in the presence of environmental fluctuations – a route congestion increase – or even abrupt variations – a server breakdown. A quite general dynamic binding problem is here reformulated as a discrete-time feedback control one, and the use of autotuning techniques is discussed, extending previous research, in a view to guaranteeing the desired quality of service without the need for computationally-intensive optimisations.
4.	Murgovski, Nikolce, 1980, et al. (författare) Dimensioning and Control of a Thermally Constrained Double Buffer Plug-in HEV Powertrain 2012 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. - 9781467320658 ; , s. 6346-6351 Konferensbidrag (refereegranskat)abstract This paper describes modeling steps to enable fast evaluation of performance and cost effectiveness of a plugin hybrid electric vehicle. The paper also shows how convex optimization can be used to dimension the vehicle powertrain while simultaneously controlling the energy buffer power. The method allows for optimal control of powertrain components that are subject to thermal constraints. The studied vehicle is a city bus driven along a perfectly known bus line. The bus is equipped with an engine-generator unit and an energy buffer consisting of an ultracapacitor and a battery. The engine generator unit and the energy buffer are modeled with quadratic power losses and are sized for two different charging scenarios. In the first scenario the bus can charge for a couple of seconds while standing still at bus stops, and in the second scenario the bus can charge for a couple of minutes before starting the route. In both scenarios, the ultracapacitor temperature is kept below a certain limit.
5.	Pettersson, Anders, et al. (författare) Analysis of Linear L1 Adaptive Control Architectures for Aerospace Applications 2012 Ingår i: IEEE 51st Annual Conference on Decision and Control (CDC), 2012. - 0743-1546. - 9781467320658 ; , s. 1136-1141 Konferensbidrag (refereegranskat)abstract In some situations the closed-loop system obtained by L1 adaptive control is equivalent to linear systems. The architectures of these systems are investigated and compared with internal model control and the input observer architecture. The analysis is focused on aerospace application. An effort has been made to understand and describe what fundamental control characteristic of flying applications that make L1 adaptive controllers suitable for the task.
6.	Sootla, Aivar, et al. (författare) Scalable Positivity Preserving Model Reduction Using Linear Energy Functions 2012 Ingår i: IEEE 51st Annual Conference on Decision and Control (CDC), 2012. - 0743-1546. - 9781467320658 ; , s. 4285-4290 Konferensbidrag (refereegranskat)abstract In this paper, we explore positivity preserving model reduction. The reduction is performed by truncating the states of the original system without balancing in the classical sense. This may result in conservatism, however, this way the physical meaning of the individual states is preserved. The reduced order models can be obtained using simple matrix operations or using distributed optimization methods. Therefore, the developed algorithms can be applied to sparse large-scale systems.
7.	Ali, Mohammad, 1982, et al. (författare) Model-Based Threat Assessment in Semi-Autonomous Vehicles with Model Parameter Uncertainties 2011 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. - 9781612848006 ; , s. 6822-6827 Konferensbidrag (refereegranskat)abstract In this paper, we consider model-based threat assessment methods which rely on vehicle and driver mathematical models and are based on reachability analysis tools and set invariance theory. We focus on the parametric uncertainties of the driver mathematical model and show how these can be accounted for in the threat assessment. The novelty of the proposed methods lies in the inclusion of the driver model uncertainties in the threat assessment problem formulation and in their validation through experimental data. We show how different ways of accounting for the model uncertainties impact the capabilities and the effectiveness of the proposed algorithms in detecting hazardous driving situations.
8.	Ali, Mohammad, 1982, et al. (författare) Threat assessment design under driver parameter uncertainty 2012 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. - 9781467320641 ; , s. 6315-6320 Konferensbidrag (refereegranskat)abstract We consider a model-based threat assessment method, which enables the activation of assisting safety interventions in case an accident threat to the driver is detected. The method relies on vehicle and driver mathematical models and reachability analysis tools. In particular, we focus on the problem of false threats detection that can occur due to uncertainties in the driver model, i.e., the driver is incorrectly deemed incapable of accomplishing a driving task. This paper proposes a novel approach, to compensate for uncertainties in the driver model, for the considered threat assessment method. In particular, we show how the considered threat assessment method can be designed such that, if a threat is detected, the driver is guaranteed to be unable to perform the assigned driving task. In such case, an automated assisting intervention can be motivated
9.	Almeida, Diogo, 1991-, et al. (författare) A Lyapunov-Based Approach to Exploit Asymmetries in Robotic Dual-Arm Task Resolution 2019 Ingår i: 58th IEEE Conference on Decision and Control (CDC). ; 2019-December, s. 4252-4258 Konferensbidrag (refereegranskat)abstract Dual-arm manipulation tasks can be prescribed to a robotic system in terms of desired absolute and relative motion of the robot’s end-effectors. These can represent, e.g., jointly carrying a rigid object or performing an assembly task. When both types of motion are to be executed concurrently, the symmetric distribution of the relative motion between arms prevents task conflicts. Conversely, an asymmetric solution to the relative motion task will result in conflicts with the absolute task. In this work, we address the problem of designing a control law for the absolute motion task together with updating the distribution of the relative task among arms. Through a set of numerical results, we contrast our approach with the classical symmetric distribution of the relative motion task to illustrate the advantages of our method.
10.	Alutto, Martina, et al. (författare) Multiple peaks in network SIR epidemic models 2022 Ingår i: 2022 IEEE 61st Conference on Decision and Control, CDC 2022. - 2576-2370 .- 0743-1546. - 9781665467612 ; 2022-December, s. 5614-5619 Konferensbidrag (refereegranskat)abstract We study network SIR (Susceptible - Infected - Recovered) epidemic models in the case of two interacting populations. We analyze the dynamics behavior of the fractions of infected individuals in the two populations. In contrast to the classical scalar SIR epidemic model, where the fraction of infected individuals is known to have an unimodal behavior (either decreasing throughout time or initially increasing, until reaching a peak and decreasing everafter), we show the possible occurrence of a novel multimodal behaviors in the network SIR model. Specifically, we show that the curve of the fraction of infected individuals in a population may incur in a change of monotonicity even when it starts with a decreasing trend. Our analysis focuses on a homogeneous mixing model, whereby all contacts have unitary frequency. We study the initial conditions and network characteristics sufficient for the aforementioned multimodal behavior to emerge and those that instead guarantee the classical unimodal behavior.
11.	Bahraini, Masoud, 1991, et al. (författare) Communication Demand Minimization for Perturbed Networked Control Systems with Coupled Constraints 2023 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. ; , s. 3468-3473 Konferensbidrag (refereegranskat)abstract Communication scheduling is needed when control loops of several safety-critical systems are closed through a shared communication medium. To enable schedulability, control for each system is designed primarily to minimize its communication demand. In this paper, we study communication demand minimization for a class of perturbed multi-agent networked control systems with a shared communication medium and subject to input and coupled state constraints. First, a framework to design communication schedule and control is recalled such that state and input constraints are satisfied under no coupling assumption. Then, a heuristic method is proposed to decouple state constraints such that the overall communication demand of the systems is minimized. Effectiveness of the proposed results are illustrated through a numerical example.
12.	Bahraini, Masoud, 1991, et al. (författare) Robust Control Invariance for Networked Control Systems with Output Feedback 2022 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 0743-1546 .- 2576-2370. ; 2022-December, s. 7676-7681 Konferensbidrag (refereegranskat)abstract This paper focuses on robust output feedback design for multi-agent networked control systems with a shared communication medium, where each system is subject to state and input constraints. We first compute the communication demand for each system given constant observer and controller gains; we argue that minimization of the communication demand with respect to the control or observer gains is very hard. Then, given a constant observer gain, we compute the minimum communication demand for each system and a corresponding control policy using model predictive control; we argue that the second approach is less difficult to solve and results in a communication demand which is no larger than for a linear controller. We illustrate and compare these design methods by a numerical example.
13.	Bengtsson, Fredrik, 1989, et al. (författare) LQG Control for Systems with Random Unbounded Communication Delay 2016 Ingår i: Proceedings of the 55th IEEE Conference on Decision and Control (CDC 2016); Las Vegas; United States; 12-14 December 2016. - 0743-1546. - 9781509018376 ; , s. Art no 7798406, Pages 1048-1055 Konferensbidrag (refereegranskat)abstract In this paper LQG control over unreliable communication links is examined. That is to say, the communication channels between the controller and the actuators and between the sensors and the controller are unreliable. This is of growing importance as networked control systems and use of wireless communication in control are becoming increasingly common. A proposed approach is to use tree codes to turn lossy channels into ones with a random delay. The problem of how to optimize LQG control in this case is examined, and it is found that to optimize LQG control previous control signals must also be used. Only the situation where communication between the components is done with acknowledgments is examined. An optimal solution is derived for finite horizon discrete hold-input LQG control for this case. The solution is compared with standard LQG control in simulations, which demonstrate that a significant improvement in the cost can be achieved when the probability of delay is high.
14.	Börve, Erik, 1998, et al. (författare) Interaction-Aware Trajectory Prediction and Planning in Dense Highway Traffic using Distributed Model Predictive Control 2023 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. ; , s. 6124-6129 Konferensbidrag (refereegranskat)abstract In this paper we treat optimal trajectory planning for an autonomous vehicle (AV) operating in dense traffic, where vehicles closely interact with each other. To tackle this problem, we present a novel framework that couples trajectory prediction and planning in multi-agent environments, using distributed model predictive control. A demonstration of our framework is presented in simulation, employing a trajectory planner using non-linear model predictive control. We analyze performance and convergence of our framework, subject to different prediction errors. The results indicate that the obtained locally optimal solutions are improved, compared with decoupled prediction and planning.
15.	Cederberg, Daniel, et al. (författare) Synthesis of Minimax Adaptive Controller for a Finite Set of Linear Systems 2022 Ingår i: 2022 IEEE 61ST CONFERENCE ON DECISION AND CONTROL (CDC). - : IEEE. - 2576-2370 .- 0743-1546. - 9781665467612 - 9781665467629 ; , s. 1380-1384 Konferensbidrag (refereegranskat)abstract The design of an adaptive controller with bounded L-2-gain from disturbances to errors for linear time-invariant systems with uncertain parameters restricted to a finite set is investigated. The synthesis of the controller requires finding matrices satisfying non-convex matrix inequalities. We propose an approach for finding these matrices based on repeatedly linearizing the terms that cause the non-convexity of the inequalities. Empirical evidence suggests that the approach leads to adaptive controllers with significantly smaller upper bound on the L-2-gain.
16.	Charalambous, Themistoklis, 1981, et al. (författare) On the Resource Allocation Problem in Wireless Networked Control Systems 2017 Ingår i: IEEE Conference on Decision and Control. - : IEEE. - 0743-1546. - 9781509028733 ; 2018-January, s. 4147-4154 Konferensbidrag (refereegranskat)abstract This paper considers the scheduling problem of a decentralized system where a number of dynamical subsystems with no computational power are scheduled to transmit their measurements via a resource-limited communication network to a remote decision maker who acts as an estimator, controller and scheduler for the subsystems. We propose a new approach for communication resource allocation for a wide class of ob- jective functions, for both coupled and decoupled systems, and for both scheduling observations as well as control commands. This framework allows to schedule over a finite horizon and can explicitly deal with stochastic channels. For decoupled subsystems, we propose the notion of cost of information loss (CoIL) and we demonstrate that the communications resource allocation problem can be directly expressed in terms of CoIL functions as an assignment-type optimization problem. Illustra- tive examples demonstrate how communication resources affect the performance of the system.
17.	Charalambous, Themistoklis, 1981, et al. (författare) Totally asynchronous distributed estimation of eigenvector centrality in digraphs with application to the PageRank problem 2016 Ingår i: 2016 IEEE 55th Conference on Decision and Control, CDC 2016. - : Institute of Electrical and Electronics Engineers (IEEE). - 0743-1546. - 9781509018376 ; , s. 25-30 Konferensbidrag (refereegranskat)abstract We propose a distributed coordination mechanism which enables nodes in a directed graph to accurately estimate their eigenvector centrality (eigencentrality) even if they update their values at times determined by their own clocks. The clocks need neither be synchronized nor have the same speed. The main idea is to let nodes adjust the weights on outgoing links to compensate for their update speed: the higher the update frequency, the smaller the link weights. Our mechanism is used to develop a distributed algorithm for computing the PageRank vector, commonly used to assign importance to web pages and rank search results. Although several distributed approaches in the literature can deal with asynchronism, they cannot handle the different update speeds that occur when servers have heterogeneous computational capabilities. When existing algorithms are executed using heterogeneous update speeds, they compute incorrect PageRank values. The advantages of our algorithm over existing approaches are verified through illustrative examples.
18.	Chen, Tianshi, et al. (författare) Sparse multiple kernels for impulse response estimation with majorization minimization algorithms 2012 Ingår i: Decision and Control (CDC), 2012. - : IEEE. - 9781467320658 - 9781467320641 ; , s. 1500-1505 Konferensbidrag (refereegranskat)abstract This contribution aims to enrich the recently introduced kernel-based regularization method for linear system identification. Instead of a single kernel, we use multiple kernels, which can be instances of any existing kernels for the impulse response estimation of linear systems. We also introduce a new class of kernels constructed based on output error (OE) model estimates. In this way, a more flexible and richer representation of the kernel is obtained. Due to this representation the associated hyper-parameter estimation problem has two good features. First, it is a difference of convex functions programming (DCP) problem. While it is still nonconvex, it can be transformed into a sequence of convex optimization problems with majorization minimization (MM) algorithms and a local minima can thus be found iteratively. Second, it leads to sparse hyper-parameters and thus sparse multiple kernels. This feature shows the kernel-based regularization method with multiple kernels has the potential to tackle various problems of finding sparse solutions in linear system identification.
19.	Cianfanelli, Leonardo, et al. (författare) Lockdown interventions in SIR models : Is the reproduction number the right control variable? 2021 Ingår i: 60th IEEE Conference on Decision and Control, CDC 2021. - 0743-1546 .- 2576-2370. - 9781665436595 ; 2021-December, s. 4254-4259 Konferensbidrag (refereegranskat)abstract The recent COVID-19 pandemic highlighted the need of non-pharmaceutical interventions in the first stages of a pandemic. Among these, lockdown policies proved unavoidable yet extremely costly from an economic perspective. To better understand the tradeoffs between economic and epidemic costs of lockdown interventions, we here focus on a simple SIR epidemic model and study lockdowns as solutions to an optimal control problem. We first show numerically that the optimal lockdown policy exhibits a phase transition from suppression to mitigation as the time horizon grows, i.e., if the horizon is short the optimal strategy is to impose severe lockdown to avoid diffusion of the infection, whereas if the horizon is long the optimal control steers the system to herd immunity to reduce economic loss. We then consider two alternative policies, motivated by government responses to the COVID19 pandemic, where lockdown levels are selected to either stabilize the reproduction number (i.e., "flatten the curve") or the fraction of infected (i.e., containing the number of hospitalizations). We compute analytically the performance of these two feedback policies and compare them to the optimal control. Interestingly, we show that in the limit of infinite horizon stabilizing the number of infected is preferable to controlling the reproduction number, and in fact yields close to optimal performance.
20.	Colombo, Alessandro, et al. (författare) Measurement Scheduling for Control Invariance in Networked Control Systems 2018 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. ; 2018-December, s. 3361-3366 Konferensbidrag (refereegranskat)abstract We discuss a new reachability problem for networked controlled system where a master node - the controller - broadcasts commands to a set of slave nodes, which must take turn to relay back state measurements. This problem finds applications in some robotics and intelligent transportation systems setups. Constraints on communication demand a coupled design of the controller and the measurement schedule. We prove that the problem is formally equivalent to the Pinwheel Problem from scheduling theory, and building on this result we provide conditions for schedulability and reachability. The results are illustrated in three numerical examples.
21.	Como, Giacomo, et al. (författare) Throughput optimal distributed routing in dynamical flow networks 2013 Ingår i: IEEE 52nd Annual Conference on Decision and Control (CDC), 2013. - 0743-1546. - 9781467357142 ; , s. 6729-6734 Konferensbidrag (refereegranskat)
22.	Crouse, David, F., et al. (författare) Aspects of MMOSPA Estimation 2011 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. - 9781612848006 ; , s. 6001-6006 Konferensbidrag (refereegranskat)abstract We expand upon existing literature regarding usingMinimum Mean Optimal Sub-Pattern Assignment (MMOSPA)estimates in multitarget tracking, noting its advantages incomparison to Maximum Likelihood (ML) and Minimum MeanSquared Error (MMSE) estimation, and look at the practicalcomputation of MMOSPA estimates. We demonstrate the useof MMOSPA estimation in a two-target tracking scenario aswell as outside of tracking in a radar angular superresolutionscenario.
23.	Dabiri, Azita, 1984, et al. (författare) Distributed dynamic output feedback control for discrete-time linear parameter varying systems 2016 Ingår i: Proceedings of IEEE Conference on Decision and Control, Las Vegas, USA, December 12-14, 2016. - 0743-1546. - 9781509018376 ; , s. Art no 7799203, Pages 6080-6085 Konferensbidrag (refereegranskat)abstract Proposed in this note, is a method for scheduleddistributed dynamic output feedback controller design. The underlying large-scale system is assumed to be the interconnection of Linear Parameter Varying (LPV) discrete time sub-systems. Following the concept of Integral Quadratic Constraints, robust LPV controller is developed aiming at L2 norm minimisation. The interconnection of the controller has been selected to be identical to the spacial distribution of the sub-systems to secure the level of sparsity in communication topology. By using agentwise full block multipliers in the design phase, distributed output feedback controller design framework is obtained by thesequential use of elimination and dualization lemmas. In order to show the benefits of the suggested methodology, numerical simulation tests are carried out to control the traffic flow in a motorway segment by means of on-ramp input flow gating.
24.	Dahlin, Albin, 1992, et al. (författare) Obstacle Avoidance in Dynamic Environments via Tunnel-following MPC with Adaptive Guiding Vector Fields 2023 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 9798350301243 ; 2023, s. 5784-5789 Konferensbidrag (refereegranskat)abstract This paper proposes a motion control scheme for robots operating in a dynamic environment with concave obstacles. A Model Predictive Controller (MPC) is constructed to drive the robot towards a goal position while ensuring collision avoidance without direct use of obstacle information in the optimization problem. This is achieved by guaranteeing tracking performance of an appropriately designed receding horizon path. The path is computed using a guiding vector field defined in a subspace of the free workspace where each point in the subspace satisfies a criteria for minimum distance to all obstacles. The effectiveness of the control scheme is illustrated by means of simulation.
25.	Damonte, Luca, et al. (författare) Targeting interventions for displacement minimization in opinion dynamics 2022 Ingår i: 2022 IEEE 61st Conference on Decision and Control, CDC 2022. - 0743-1546 .- 2576-2370. - 9781665467612 ; 2022-December, s. 7023-7028 Konferensbidrag (refereegranskat)abstract Social influence is largely recognized as a key factor in opinion formation processes. Recently, the role of external forces in inducing opinion displacement and polarization in social networks has attracted significant attention. This is in particular motivated by the necessity to understand and possibly prevent interference phenomena during political campaigns and elections. In this paper, we formulate and solve a targeted intervention problem for opinion displacement minimization on a social network. Specifically, we consider a min-max problem whereby a social planner (the defender) aims at selecting the optimal network intervention within her given budget constraint in order to minimize the opinion displacement in the system that an adversary (the attacker) is instead trying to maximize. Our results show that the optimal intervention of the defender has two regimes. For large enough budget, the optimal intervention of the social planner acts on all nodes proportionally to a new notion of network centrality. For lower budget values, such optimal intervention has a more delicate structure and is rather concentrated on a few target individuals.
26.	De Benedittis, Giacomo, et al. (författare) Intersection Crossing of Autonomous Vehicles for Communication Links with Packet Losses 2022 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. ; 2022-December, s. 7656-7662 Konferensbidrag (refereegranskat)abstract This work aims at addressing the problem of intersection crossing for autonomous vehicles in the presence of a lossy communication channel (that may cause the loss of data packets in the communication) between the vehicle and a central coordinator. This work aims to provide a solution that guarantees the crossing of the intersection, despite the packet losses. Our approach consists of an optimal control algorithm in which at every time step the optimal control sequence simulating a communication ensemble between the vehicle and the coordinator is computed. Since the model is stochastic and the channel imperfect, the intersection crossing condition is modeled as a chance constraint. Once the control sequence is found, the first step is applied and the optimization is performed again over a shrunk horizon. A real-time state observer using optimal Kalman filter observation gains is used. The performance of our approach is tested on a simplified dynamic car model. The sensitivity of the generated control sequence with respect to some key parameters (such as failure probability allowed and packet drop probability) is also considered.
27.	Dimitrakakis, Christos, 1975 (författare) Monte-Carlo utility estimates for Bayesian reinforcement learning 2013 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. - 9781467357173 ; , s. 7303-7308 Konferensbidrag (refereegranskat)abstract This paper introduces a set of algorithms for Monte-Carlo Bayesian reinforcement learning. Firstly, Monte-Carlo estimation of upper bounds on the Bayes-optimal value function is employed to construct an optimistic policy. Secondly, gradient-based algorithms for approximate upper and lower bounds are introduced. Finally, we introduce a new class of gradient algorithms for Bayesian Bellman error minimisation. We theoretically show that the gradient methods are sound. Experimentally, we demonstrate the superiority of the upper bound method in terms of reward obtained. However, we also show that the Bayesian Bellman error method is a close second, despite its significant computational simplicity.
28.	Fei, Zhennan, 1984, et al. (författare) Symbolic computation and representation of deadlock avoidance policies for complex resource allocation systems with application to multithreaded software 2015 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 0743-1546 .- 2576-2370. ; 2015-February, s. 5935-5942 Konferensbidrag (refereegranskat)abstract In our recent work, we proposed a series of binary decision diagram (BDD-) based approaches for developing the maximally permissive deadlock avoidance policy (DAP) for a class of complex resource allocation systems (RAS). In this paper, (i) we extend these approaches by introducing a procedure that generates a set of comprehensible 'guard' predicates to represent the resulting DAP, and (ii) we customize them to the problem of deadlock avoidance in shared-memory multithreaded software, that has been previously addressed by the Gadara project. In the context of this last application, the generated guards can be instrumented directly into the source code of the underlying software threads, providing, thus, a very efficient and natural representation of the target policy. At the same time, by integrating the representational and computational strengths of symbolic computation, the presented approach can support the computation of the maximally permissive DAP for RAS corresponding to problem instances of even larger scale and complexity than those addressed in the current literature.
29.	Feyzmahdavian, Hamid Reza, et al. (författare) Delay-independent stability of cone-invariant monotone systems 2016 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - : IEEE. - 0743-1546 .- 2576-2370. - 9781479978861 ; 2016-February, s. 6361-6366, s. 6361-6366 Konferensbidrag (refereegranskat)abstract Recent results in the literature have shown that particular classes of positive systems are insensitive to time-varying delays, giving the impression that the delay-insensitivity property stems from the fact that the system is positive. Nonetheless, it has been lately shown that a linear cone-invariant system is insensitive to time-varying delays, asserting that the property of delay-independence may stem from the fact that the system is cone-invariant rather than positive. In this paper, we provide additional evidence for this claim by analyzing the stability of cone-invariant monotone systems with bounded time-varying delays. We present a set of sufficient conditions for delay independent stability of discrete- and continuous-time cone-invariant monotone systems. For linear cone-invariant systems, we show that the stability conditions we have derived are also necessary.
30.	Ghoddousiboroujeni, M., et al. (författare) Privacy of Real-Time Pricing in Smart Grid 2019 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - : Institute of Electrical and Electronics Engineers Inc.. - 9781728113982 ; 2019-December, s. 5162-5167 Konferensbidrag (refereegranskat)abstract Installing smart meters to publish real-time electricity rates has been controversial while it might lead to privacy concerns. Dispatched rates include fine-grained data on aggregate electricity consumption in a zone and could potentially be used to infer a household's pattern of energy use or its occupancy. In this paper, we propose Blowfish privacy to protect the occupancy state of the houses connected to a smart grid. First, we introduce a Markov model of the relationship between electricity rate and electricity consumption. Next, we develop an algorithm that perturbs electricity rates before publishing them to ensure users' privacy. Last, the proposed algorithm is tested on data inspired by household occupancy models and its performance is compared to an alternative solution.
31.	Gros, Sébastien, 1977 (författare) A distributed algorithm for NMPC-based wind farm control 2015 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 0743-1546 .- 2576-2370. ; , s. 4844-4849 Konferensbidrag (refereegranskat)abstract Nonlinear Model Predictive Control (NMPC) has been identified as a highly promising control technique for wind turbine generators, and has been shown to be realtime feasible for the control of individual wind turbines. The potential benefit of performing control at the wind farm level is well understood, and has been recently investigated in the literature. Likewise, the extension of NMPC from wind turbine to wind farm control is highly desirable, but very challenging since it requires solving large non-convex optimal control problems in real time. It has not been considered so far in the literature. This paper proposes a first contribution in that direction, using a distributed optimisation approach based on the Lagrange relaxation. The proposed algorithm requires a very limited amount of additional computations when compared to controlling the wind turbines individually via NMPC. The problem of smoothing the wind farm power output is considered here.
32.	Gros, Sébastien, 1977 (författare) A Newton algorithm for distributed Semi-Definite Programs using the primal-dual interior-point method 2015 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. ; , s. 3222-3227 Konferensbidrag (refereegranskat)abstract This paper considers the problem of solving convex decomposable Semi-Definite Programs (SDPs) in a distributed fashion. The SDP subproblems are solved locally, while the constraints coupling the different local problems are introduced in the local cost functions using a Lagrange relaxation. The local problems are solved via the primal-dual interior-point method, taking steps along the Nesterov-Todd directions, while the feasibility of the coupling constraints is improved along the central path by taking Newton iterations on the multipliers associated to the Lagrange relaxation. The local factorisations involved in computing the Nesterov-Todd directions are re-used to construct gradients and Hessians for the Lagrange multipliers. The local factorisations are also re-used to construct linear predictors for both the local primal-dual variables and the multipliers, which improve significantly the tracking of the central path.
33.	Gros, Sébastien, 1977, et al. (författare) An improved real-time economic NMPC scheme for Wind Turbine control using spline-interpolated aerodynamic coefficients 2015 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. ; , s. 935-940 Konferensbidrag (refereegranskat)abstract Nonlinear Model Predictive Control (NMPC) is a strong candidate for the control of large Multi-Mega Watt Wind Turbine Generators (WTG), especially when reliable Light Detection And Ranging (LIDAR) systems are available. Recently, a real-time NMPC for WTG control has been proposed, but had a limited reliability if deployed over the full WTG operating range due to the difficulty of handling the WTG aerodynamic coefficients over a large domain and of using a Gauss-Newton Hessian. In this paper, we address these two issues. A fast surface B-spline code has been developed specifically to tackle the interpolation of the aerodynamic coefficients for NMPC-based WTG control. A novel Hessian approximation for the NMPC problem is used, for which an efficient and inexpensive regularization is proposed. The approach presented is real-time feasible, and accurate over the full operating range of the WTG.
34.	Gros, Sébastien, 1977, et al. (författare) Baumgarte Stabilisation over the SO(3) Rotation Group for Control 2015 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. - 9781479978861 ; 54rd IEEE Conference on Decision and Control,CDC 2015, s. 620-625 Konferensbidrag (refereegranskat)abstract Representations of the SO(3) rotation group are crucial for airborne and aerospace applications. Euler angles is a popular representation in many applications, but yield models having singular dynamics. This issue is addressed via non-singular representations, operating in dimensions higher than 3. Unit quaternions and the Direction Cosine Matrix are the best known non-singular representations, and favoured in challenging aeronautic and aerospace applications. All non-singular representations yield invariants in the model dynamics, i.e. a set of nonlinear algebraic conditions that must be fulfilled by the model initial conditions, and that remain fulfilled over time. However, due to numerical integration errors, these conditions tend to become violated when using standard integrators, making the model inconsistent with the physical reality. This issue poses some challenges when non-singular representations are deployed in optimal control. In this paper, we propose a simple technique to address the issue for classical integration schemes, establish formally its properties, and illustrate it on the optimal control of a satellite.
35.	Heiker, Carl-Johan, 1993, et al. (författare) Decision Modeling in Markovian Multi-Agent Systems 2022 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. - 9781665467612 ; , s. 7235-7240 Konferensbidrag (refereegranskat)abstract In this paper, we model a decision-making process involving a set of interacting agents. We use Markovian opinion dynamics, where each agent switches between decisions according to a continuous time Markov chain. Existing opinion dynamics models are extended by introducing attractive and repulsive forces that act within and between groups of agents, respectively. Such an extension enables the resemblance of behaviours emerging in networks where agents make decisions that depend both on their own preferences and the decisions of specific groups of surrounding agents. The considered modeling problem and the contributions in this paper are inspired by the interaction among road users (RUs) at traffic junctions, where each RU has to decide whether to go or to yield.
36.	Hostettler, Roland, et al. (författare) Extended Kalman filter for vehicle tracking using road surface vibration measurements 2013 Ingår i: IEEE 51st Annual Conference on Decision and Control. - Piscataway, NJ : IEEE Communications Society. - 9781467320658 - 9781467320641 Konferensbidrag (refereegranskat)abstract This paper addresses a novel method for vehicle tracking using an extended Kalman filter and measurements of road surface vibrations from a single accelerometer. First, a measurement model for vibrations caused by vehicular road traffic is developed. Then the identifiability of the involved parameters is analyzed. Finally, the measurement model is combined with a constant speed motion model and the Kalman filter is derived. Simulation and measurement results indicate that the approach is feasible and show where further development is needed.
37.	Hult, Robert, 1984, et al. (författare) An MIQP-based heuristic for Optimal Coordination of Vehicles at Intersections 2018 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. ; December 2018, s. 2783-2790 Konferensbidrag (refereegranskat)abstract The problem of coordinating automated vehicles at intersections can be formulated as an optimal control prob- lem which is inherently difficult to solve, due to its combinato- rial nature. In this paper, we propose a two-stage approximation algorithm based on a previously presented decomposition. The procedure (a) first solves a Mixed Integer Quadratic Program (MIQP) to compute an approximate solution to the combinatorial part of the problem, i.e. the order in which the vehicles cross the intersection; then (b), solves a Nonlinear Program (NLP) for the optimal state and control trajectories. We demonstrate the performance of the algorithm through extensive simulation, and show that it greatly outperforms the natural First-Come-First-Served heuristic.
38.	Jha, Prabhat Kumar, 1997, et al. (författare) Games for Efficient Supervisor Synthesis 2023 Ingår i: IEEE Control Systems Letters. - : IEEE. - 2475-1456. ; 62, s. 7228-7233 Tidskriftsartikel (refereegranskat)abstract In recent years, there has been an increasing interest in the connections between supervisory control theory and reactive synthesis. As the two fields use similar techniques there is great hope that technologies from one field could be used in the other. In this spirit, we provide an alternative reduction from the supervisor synthesis problem to solving Büchi games via games with a non-blocking objective. Our reduction is more compact and uniform than previous reductions. As a consequence, it gives an asymptotically better upper bound on the time complexity of the supervisory control synthesis problem. Our reduction also breaks a widely held belief about the impossibility of reducing the supervisory control synthesis problem to a game with a linear winning condition.
39.	Josephrexon, Brindha Jeniefer, et al. (författare) Experimenting with networked control software subject to faults 2022 Ingår i: 2022 IEEE 61st Conference on Decision and Control, CDC 2022. - 2576-2370 .- 0743-1546. - 9781665467612 ; 2022-December, s. 1547-1552 Konferensbidrag (refereegranskat)abstract Faults and errors are common in the execution of digital controllers on top of embedded hardware. Researchers from the embedded system domain devised models to understand and bound the occurrence of these faults. Using these models, control researchers have demonstrated robustness properties of control systems, and of their corresponding digital implementations. In this paper, we build a framework to experiment with the injection of faults in a networked control system that regulates the behaviour of a Furuta pendulum. We use the software framework to experiment on computational problems that cause the control signals not to be available on time, and network faults that cause dropped packets during the transmission of sensor data and actuator commands.
40.	Kjellqvist, Olle, et al. (författare) Learning Optimal Team-Decisions 2022 Ingår i: 2022 IEEE 61st Conference on Decision and Control, CDC 2022. - 0743-1546 .- 2576-2370. - 9781665467612 ; 2022-December, s. 1441-1446 Konferensbidrag (refereegranskat)abstract In this paper, we linear quadratic team decision problems, where a team of agents minimizes a convex quadratic cost function over T time steps subject to possibly distinct linear measurements of the state of nature. We assume that the state of nature is a Gaussian random variable and that the agents do not know the cost function nor the linear functions mapping the state of nature to their measurements. We present a gradient-descent based algorithm with an expected regret of O(log(T)) for full information gradient feedback and O(√(T)) for bandit feedback. In the case of bandit feedback, the expected regret has an additional multiplicative term O(d) where d reflects the number of learned parameters.
41.	Kjellqvist, Olle, et al. (författare) On Infinite-horizon System Level Synthesis Problems 2022 Ingår i: 2022 IEEE 61st Conference on Decision and Control, CDC 2022. - 0743-1546 .- 2576-2370. - 9781665467612 ; 2022-December, s. 5238-5244 Konferensbidrag (refereegranskat)abstract System level synthesis is a promising approach that formulates structured optimal controller synthesis problems as convex problems. This work solves the distributed linear-quadratic regulator problem under communication constraints directly in infinite-dimensional space, without the finite-impulse response relaxation common in related work. Our method can also be used to construct optimal distributed Kalman filters with limited information exchange. We combine the distributed Kalman filter with state-feedback control to perform localized LQG control with communication constraints. We provide agent-level implementation details for the resulting output-feedback state-space controller.
42.	Kjellqvist, Olle, et al. (författare) v-Analysis : A New Notion of Robustness for Large Systems with Structured Uncertainties 2022 Ingår i: 2022 IEEE 61st Conference on Decision and Control, CDC 2022. - 2576-2370 .- 0743-1546. - 9781665467612 ; 2022-December, s. 2361-2366 Konferensbidrag (refereegranskat)abstract We present a new, scalable alternative to the structured singular value, which we call v, provide a convex upper bound, study their properties and compare them to l1 robust control. The analysis relies on a novel result on the relationship between robust control of dynamical systems and non-negative constant matrices.
43.	Klintberg, Emil, 1989, et al. (författare) A primal active-set minimal-representation algorithm for polytopes with application to invariant-set calculations 2018 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. ; 2018-December, s. 6862-6867 Konferensbidrag (refereegranskat)abstract This paper provides a description of a practically efficient minimal-representation algorithm for polytopes. The algorithm is based on a primal active-set method that heavily exploits warm-starts and low-rank updates of matrix factorizations in order to reduce the required computational work. By using a primal active-set method, several nonredundant inequalities can be identified for each solved linear program. Implementation details are provided both for the minimalrepresentation algorithm and for the underlying active-set method.
44.	Klintberg, Emil, 1989, et al. (författare) A Primal-Dual Newton Method for Distributed Quadratic Programming 2015 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. ; , s. 5843-5848 Konferensbidrag (refereegranskat)abstract This paper considers the problem of solving Quadratic Programs (QP) arising in the context of distributed optimization and optimal control. A dual decomposition approach is used, where the problem is decomposed and solved in parallel, while the coupling constraints are enforced via manipulating the dual variables. In this paper, the local problems are solved using a primal-dual interior point method and the dual variables are updated using a Newton iteration, providing a fast convergence rate. Linear predictors for the local primaldual variables and the dual variables are introduced to help the convergence of the algorithm. We observe a fast and consistent practical convergence for the proposed algorithm.
45.	Klintberg, Emil, 1989, et al. (författare) An improved dual Newton strategy for scenario-tree MPC 2016 Ingår i: Proceedings of the 55th IEEE Conference on Decision and Control (CDC 2016); Las Vegas; United States; 12-14 December 2016. - 0743-1546. - 9781509018376 ; , s. Art no 7798822, Pages 3675-3681 Konferensbidrag (refereegranskat)abstract This paper considers the problem of solving Quadratic Programs (QPs) in the context of robust Model Predictive Control (MPC) based on scenario trees. A Newton strategy is used in conjunction with dual decomposition, yield- ing a parallelizable method with a fast practical convergence. In this context, it has been observed that the Hessian of the dual function has an intricate sparsity structure and can be rank deficient, hence requiring a computationally expensive linear algebra and a regularization strategy. In this paper, we show that it is possible to organize the robust MPC problem such that the dual Hessian has a block-tridiagonal structure, hence reducing dramatically the cost of its factorization. Moreover, a simple and inexpensive strategy of constraint elimination is pro- posed for ensuring the positive definiteness of the dual Hessian, making regularization superfluous. This strategy additionally allows for evening the computational burden of computing the robust MPC solution in its parallelization.
46.	Kojchev, Stefan, 1992, et al. (författare) An iterative algorithm for volume maximization of N-step backward reachable sets for constrained linear time-varying systems 2021 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. ; 2021-December, s. 5027-5032 Konferensbidrag (refereegranskat)abstract In this paper, we consider the computation of robust N-step backward reachable sets for state-and input con-strained linear time-varying systems with additive uncertainty. We propose a method to compute a linear, time-varying control law that maximizes the volume of the robust N-step reachable set for the closed-loop system. The proposed method is an extension of recent developments and involves the recursive solution of N semi-definite programs (SDP). We demonstrate the performance of the proposed method on the lateral control problem for emergency maneuvers of autonomous vehicles and compare it to results obtained when backward reachability is applied to the same system and a naively designed controller.
47.	Kojchev, Stefan, 1992, et al. (författare) Energy Efficient Optimization-Based Coordination of Electric Automated Vehicles in Confined Areas 2023 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. ; , s. 3433-3440 Konferensbidrag (refereegranskat)abstract In this paper, we present an optimization-based control strategy for coordinating multiple electric automated vehicles (AVs) in confined sites. The approach focuses on obtaining and keeping energy-efficient driving profiles for the AVs while avoiding collisions in cross-intersections, narrow roads, and merge crossings. Specifically, the approach is composed of two optimization-based components. The first component obtains the energy-efficient profiles for each individual AV by solving a Nonlinear Program (NLP) for the vehicle's complete mission route. The conflict resolution, which is performed by the second component, is accomplished by solving a time-scheduling Mixed Integer Linear Programming (MILP) problem that exploits the application characteristics. We demonstrate the performance of the algorithm through a non-trivial comparative simulation example with an alternative optimization-based heuristic.
48.	Kojchev, Stefan, 1992, et al. (författare) Quadratic approximation based heuristic for optimization-based coordination of automated vehicles in confined areas 2022 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. ; 2022-December, s. 6156-6162 Konferensbidrag (refereegranskat)abstract We investigate the problem of coordinating multiple automated vehicles (AVs) in confined areas. This problem can be formulated as an optimal control problem (OCP) where the motion of the AVs is optimized such that collisions are avoided in cross-intersections, merge crossings, and narrow roads. The problem is combinatorial and solving it to optimality is prohibitively difficult for all but trivial instances. For this reason, we propose a heuristic method to obtain approximate solutions. The heuristic comprises two stages: In the first stage, a Mixed Integer Quadratic Program (MIQP), similar in construction to the Quadratic Programming (QP) sub-problems in Sequential Quadratic Programming (SQP), is solved for the combinatorial part of the solution. In the second stage, the combinatorial part of the solution is held fixed, and the optimal state and control trajectories for the vehicles are obtained by solving a Nonlinear Program (NLP). The performance of the algorithm is demonstrated by a simulation of a non-trivial problem instance.
49.	Köroglu, Hakan, 1971 (författare) H Infinity Synthesis with Unstable Weighting Filters: An LMI Solution 2013 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 2576-2370 .- 0743-1546. - 9781467357142 ; , s. 2429-2434 Konferensbidrag (refereegranskat)abstract Synthesis of a controller is considered for achievinga desired level of guaranteed worst-case energy gain performance in the case of unstable (input and output) weighting filters. The solution of this problem is shown to require a proper replication of the unstable filter dynamics accompanied by a controller of free structure. By merging the replicated filter dynamics with the plant, the problem is reformulated as the design of the free part of the controller in a way to stabilize an extended plant and ensure the considered performance objective. A solution is then provided based on LMI conditions accompanied by affine equation constraints. A procedure is also outlined for the synthesis of a controller whose order is equal to the order of the plant plus the orders of the filters.
50.	Köroglu, Hakan, 1971, et al. (författare) Joint Synthesis of Dynamic Feed-Forward and Static State Feedback for Platoon Control 2014 Ingår i: Proceedings of the IEEE Conference on Decision and Control. - 0743-1546 .- 2576-2370. ; , s. 4503-4508 Konferensbidrag (refereegranskat)abstract Joint synthesis of static state-feedback and dynamic feed-forward is considered for a homogenous platoon operating under the leader and predecessor following scheme. The problem is formulated with two H-infinity type performance objectives. The first objective requires the first vehicle to respond in a desirable way to the maneuvers of the leader and it is to be realized by a joint synthesis of the feed-forward filter together with a state feedback gain. Novel LMI conditions are derived for this objective by fixing the order and the poles of the filter. The second objective aims at preventing the amplification of the errors backward along the platoon, while also maintaining robustness against communication problems with the leader. New sufficient LMI conditions are provided for this objective, based on which leader and predecessor feedback gain matrices can be constructed.

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